The present disclosure relates to a solid bowl helical conveyor centrifuge including a rotatable drum having a horizontally-oriented axis of rotation. Also included is a rotatable screw arranged in the rotatable drum and at least one discharge opening oriented at an angle with respect to the horizontally-oriented axis of rotation. The at least one discharge opening is configured to discharge solids from the rotatable drum. An adjusting device is assigned to the at least one discharge opening by which adjusting device an outlet cross-section of the at least one discharge opening is changeable. The adjusting device includes a movable adjusting disk arranged in the rotatable drum as an extension of the rotatable screw and which movable adjusting disk is non-rotatably connected with one or more of the following: a) the rotatable drum, b) the rotatable screw, and c) a screw body.
From German Patent Document DE 43 20 265 A1, a solid bowl helical conveyor centrifuge is known which is provided with a weir on the liquid outlet side which has a passage to which an orifice plate is assigned which, during the rotation of the drum, stands still relative to the latter and which, in turn, is axially displaceable by way of a threaded bush. By rotation of the threaded bush, the distance between the weir and the orifice plate can be changed. The resulting change of the discharge cross-section causes a change of the liquid level in the centrifugal drum, so that a continuous adjustment of this liquid level is permitted by the displacement of the orifice plate. However, an adjustment of the discharge of the solids cannot take place.
From European Patent Document EP 0 747 127 B1, it is known to arrange a particularly radially adjustable flow regulating element between worm or screw channels in the conical area of the worm. In this case, a relatively long adjusting path has to be bridged in order to implement a change of the outlet cross-section for the solids.
In contrast, German Patent Document DE 41 19 003 A1, in turn, shows a type of adjustable disk in the transition between the cone and the cylindrical area of the drum and the worm. The adjustment takes place through the worm. The function is that of a baffle plate which also influences the liquid level in the drum.
From European Patent EP 0 565 268 A1, it is known to provide worm channels only in the cylindrical part of a worm body and to place a type of retaining disk at the axial end of the worm body. Among other things, it is a problem that a worm or screw construction has to be selected which basically differs from conventional worm constructions.
From European Patent Document EP 0 798 045 A1, it is known to assign a throughput control device to the discharge opening for the solids. This device is arranged at the exterior side of the drum shell, which is to permit an easy visual inspection of the throughput control device. However, the implementation of the adjustability of the throughput control device at the exterior side of the drum rotating during the operation is relatively problematic because it is not close to the center but has to be implemented on a relatively large diameter where the peripheral speed is relatively high.
With respect to the prior art, Japanese Patent Documents JP 2002 153771A and JP 2003 153772A a well as German Patent Documents DE 41 19 033 A1 and DE 39 21 327 A1 are also known.
A centrifuge is also known from German Patent Document DE 1 823 269. In this document, the non-existent adjustability of the adjusting cone as well as the adjusting device of FIG. 2 by way of a torsional nut from the outside, which requires very high constructional expenditures and is relatively complicated, are problems of some embodiments. An automatic adjusting of the adjusting cone against a spring is also disclosed which, however, in practice does not lead to satisfactory results.
The present disclosure relates to a centrifuge that addresses problems referred to above.